Transgenic Corn Boosts Yields

A new kind of transgenic hybrid - called glutamate dehydrogenase (GDH) corn - does more than provide crop protection, the usual biotech feature.

"The GDH gene is novel in that it boosts yield rather than simply protects it," says David Lightfoot, a plant biotechnologist at Southern Illinois University (SIU).

"GDH corn increases nitrogen uptake, yields and protein content, as well as helps the corn plant overcome stresses, especially early in the growing cycle."

Developed at SIU, the transgenic hybrid incorporates GDH, a gene isolated from soil-borne microorganisms and then inserted into corn tissue.

Lightfoot's initial research, begun in 1991, was partially funded by the Illinois Corn Promotion Board to find a way to reduce nitrogen runoff from cornfields.

"In the typical field, a seedling corn plant is in contact with a lot of nitrogen - more than it can make use of right away," says Lightfoot.

"In even the best-managed growing systems, 10% or more of the nitrogen is lost. We saw GDH as a way to let young corn plants utilize more nitrogen. That would reduce the loss of nitrogen that a farmer buys and also reduce the amount of environmental damage caused by nitrogen runoff."

GDH has fulfilled that promise and then some. For reasons he doesn't completely understand, Lightfoot finds that corn plants equipped with the gene are bigger and more productive all the way through the growing season.

"In another year, we should produce enough volume to hold mass feeding trials," he says.

GDH corn is just a tip of the biotechnology iceberg, says Lightfoot.

"I think yield-boosting genes will be bred into more hybrids in the next few years. And we will be able to tackle some other yield-limiting factors genetically - the limit on yields from moisture shortage, for example."